1. Field of the Invention
The present invention relates to a controller for an electric heating device and a method for producing the same.
2. Discussion of the Related Art
The present invention relates in particular to a controller for an electric heating device with the features according to the preamble of claim 1. Such a controller is for example known from EP 2 043 412 A1. This controller comprises a circuit board and a busbar, which is secured on this support element and which is connected to an SMD component in an electrically conductive manner.
The SMD component usually is a power semiconductor switch producing power loss. This power loss needs to be continuously discharged. Thus, the busbar of the aforementioned prior art also constitutes a heat sink, which is connected to a separate heat sink, the cooling ribs of which essentially protrude perpendicularly from the support element. The SMD component is arranged on one side of the support element, the heat sink on the other side.
The applicant knows a plurality of solutions on how, also by taking into account the necessary discharge of the thermal loss, the busbar may be configured in order to meet practical requirements. Such solutions are for example known from DE 10 2005 038 862 A1, JP 2001-319708, DE 195 18 522 A1, EP 1 395 098 A1, CN 2727957 Y, DE 199 35 803 A1, DE 10 2004 061 936 A1, EP 0 901 166 A1, U.S. Pat. No. 6,442,033 B1.
The previously known solution from EP 2 043 412 A1 is unfavorable in terms of thermal technology, since due to the arrangement of the SMD component, the thermal conduction distance up to the cooling ribs is relatively long. Moreover, producing is complex and cost-intensive. Finally, the solution is unsatisfactory, since the power flow exclusively is conducted via a single busbar. The circuit board, however, only has a limited capacity for transmitting high power flows.
Specifically, the last-mentioned aspect is important for controllers for electric heating devices, since relatively high power flows are controlled or switched there. Furthermore, the present invention in particular aims to provide a controller for an electric heating device in a motor vehicle. Such electric heating devices and their controllers require specific safety standards. The operating conditions in a motor vehicle further require a very good and solid contacting of all components involved. Vibrations, cold differences, as well as where appropriate humid and contaminated atmosphere, especially require a good contacting and a solid transmission of the power flow. Contact resistances in the conductive track of the power flow often lead to a local heating, which may lead to the alloying of the SMD component. A thermal event may lead to smoldering of the entire controller or the entire heating device.